Many Medicare Advantage enrollees consider switching back to Original Medicare at some point. The reasons vary — dissatisfaction with network restrictions, difficulty getting referrals, or a desire for broader provider access. But making this switch involves a risk that catches many people off guard: you may not be able to purchase a Medigap (Medicare Supplement) plan to cover the cost-sharing gaps in Original Medicare.
This article explains how Medigap underwriting works, when you have guaranteed issue rights, when you do not, and what steps you can take to protect yourself.
Why Medigap Matters When You Return to Original Medicare
Original Medicare covers a wide range of services, but it leaves you responsible for significant out-of-pocket costs. For 2026, the Part B deductible is $257, and after meeting it, you generally pay 20% coinsurance on Part B services with no annual out-of-pocket maximum. Hospital stays carry their own deductibles and coinsurance under Part A.
A single surgery, extended hospital stay, or series of specialist visits can produce thousands of dollars in cost-sharing. Medigap plans are designed to absorb some or all of those expenses, depending on the plan type you choose.
Without a Medigap plan, you are on Original Medicare alone and exposed to those costs with no cap on what you could owe in a given year. This is a meaningful difference from Medicare Advantage, which is required to include an annual out-of-pocket limit.
The Medigap Underwriting Trap
Here is the core issue: outside of specific enrollment windows and qualifying events, Medigap insurers in most states can evaluate your health before deciding whether to sell you a policy. This process is called medical underwriting.
During underwriting, the insurer may:
- Ask health questions about your current conditions, medications, recent treatments, hospitalizations, and planned surgeries
- Deny your application based on your medical history
- Charge higher premiums if they determine you present an elevated risk
- Impose a pre-existing condition exclusion period of up to six months, during which the plan will not cover expenses related to conditions you were diagnosed with or treated for before the policy started
Conditions that commonly trigger denials or higher premiums include diabetes with complications, heart disease, COPD, cancer (recent or under treatment), stroke history, kidney disease, and other serious chronic conditions. Each insurer sets its own underwriting criteria, so a condition that leads to denial with one company may not with another — but there is no guarantee of approval.
If you have been enrolled in a Medicare Advantage plan for several years and have developed health conditions during that time, you may find that no Medigap insurer in your area is willing to sell you a policy at standard rates — or at all.
Guaranteed Issue Rights: When Insurers Cannot Deny You
Federal law provides specific situations, known as guaranteed issue rights, where a Medigap insurer must sell you a policy regardless of your health. Understanding these situations is essential before making any switch.
Your Initial Medigap Open Enrollment Period
When you first turn 65 and enroll in Medicare Part B, you have a six-month Medigap Open Enrollment Period. During this window, you can buy any Medigap plan sold in your state, and the insurer cannot deny you coverage or charge more due to health conditions. This is your single strongest enrollment opportunity under federal law.
The Medicare Advantage Trial Right
If you enrolled in a Medicare Advantage plan when you were first eligible for Medicare (at age 65 or during your Initial Enrollment Period), you have a 12-month trial right. If you decide within those first 12 months that the Medicare Advantage plan is not right for you, you can disenroll, return to Original Medicare, and purchase a Medigap plan with guaranteed issue protections. You must apply for the Medigap policy no later than 63 days after your Medicare Advantage coverage ends.
This trial right also applies if you dropped a Medigap plan to join a Medicare Advantage plan for the first time. If you leave the MA plan within 12 months, you have the right to get your old Medigap plan back (if the insurer still sells it) or purchase Medigap Plan A, B, C, F, K, or L.
Other Guaranteed Issue Situations
You may also have guaranteed issue rights if:
- Your Medicare Advantage plan leaves your area or stops offering coverage, and you lose your plan through no fault of your own
- Your Medicare Advantage plan commits a contract violation or misleads you about coverage
- Your employer-sponsored retiree coverage ends and you need to transition to individual Medigap coverage
- Your Medigap insurer goes bankrupt or you otherwise involuntarily lose your Medigap policy
In these situations, you generally have 63 days from the date your prior coverage ends to apply for a Medigap policy with guaranteed issue protections. The specific Medigap plan letters available to you may vary depending on the qualifying event.
When You Do Not Have Guaranteed Issue Rights
If you have been on a Medicare Advantage plan for more than 12 months and none of the qualifying events above apply, you generally do not have federal guaranteed issue rights to purchase a Medigap plan. This is the scenario where many beneficiaries run into trouble.
For example, if you enrolled in Medicare Advantage three years ago and now decide you want to return to Original Medicare during the Medicare Advantage Open Enrollment Period (January 1 through March 31), you can leave your MA plan — but securing a Medigap policy may require passing medical underwriting. If your health has changed since you first enrolled, this could mean higher premiums, a waiting period for pre-existing conditions, or outright denial.
The Medicare Advantage Open Enrollment Period (MA OEP)
The MA OEP runs from January 1 through March 31 each year. During this window, current Medicare Advantage enrollees can:
- Switch to a different Medicare Advantage plan
- Drop their Medicare Advantage plan and return to Original Medicare (with the option to enroll in a standalone Part D plan)
The MA OEP is not the same as the Annual Election Period (October 15 through December 7). It is specifically for people who are already enrolled in a Medicare Advantage plan and want to make a change.
An important distinction: the MA OEP does not grant Medigap guaranteed issue rights. If you use this period to leave Medicare Advantage and return to Original Medicare, you will still need to go through medical underwriting for a Medigap plan unless you qualify for guaranteed issue through one of the situations described above or live in a state with additional protections.
State-Specific Protections
While federal guaranteed issue rights are limited, some states have enacted stronger consumer protections for Medigap enrollment. These protections vary significantly by state.
Continuous Open Enrollment States
A small number of states require Medigap insurers to sell policies to Medicare beneficiaries ages 65 and older at any time of year, without medical underwriting:
- Connecticut — Continuous guaranteed issue year-round. Insurers must sell you a Medigap policy regardless of your health status.
- New York — Continuous guaranteed issue year-round, similar to Connecticut.
- Massachusetts — State law mandates a guaranteed issue period from February 1 through March 31 each year. In practice, Medigap carriers in the state generally offer year-round guaranteed issue enrollment.
- Maine — Requires an annual one-month guaranteed issue window, though the available plan options may be more limited.
If you live in one of these states, the risk of being denied a Medigap policy after leaving Medicare Advantage is substantially lower.
Birthday Rule States
Several states offer an annual birthday rule that allows existing Medigap policyholders to switch to a different Medigap plan (of equal or lesser benefits) around their birthday without medical underwriting. States with some form of birthday rule include California, Oregon, Illinois, Idaho, Louisiana, Nevada, Maryland, and Oklahoma. The details — including the length of the enrollment window and eligible plan changes — differ by state.
Note that birthday rules typically apply to people who already have a Medigap plan and want to change plans. They generally do not help someone who is purchasing Medigap for the first time after leaving Medicare Advantage.
Other State Protections
Some states offer additional protections beyond the federal minimum, such as extended open enrollment windows or annual guaranteed issue periods for specific populations. Contact your State Health Insurance Assistance Program (SHIP) to learn what protections are available where you live. SHIP counselors provide free, unbiased guidance and can explain your state's specific rules.
What Happens If You Cannot Get a Medigap Plan
If you return to Original Medicare and are unable to obtain a Medigap policy, you have several realities to consider:
Staying on Original Medicare Without a Supplement
You can remain on Original Medicare without any supplemental coverage. However, you will be responsible for:
- The Part B premium ($203.90 per month in 2026) plus any IRMAA surcharges based on income
- The Part B deductible ($257 in 2026) and 20% coinsurance on covered services, with no annual cap
- Part A deductibles and coinsurance for hospital stays, skilled nursing facility care, and other inpatient services
- Any costs for services Original Medicare does not cover
For a healthy year with minimal medical needs, this arrangement may be manageable. But a serious illness or injury could lead to substantial out-of-pocket expenses.
Considering a Medicare Advantage Plan Instead
If you cannot obtain Medigap coverage, you may want to consider re-enrolling in a Medicare Advantage plan. Medicare Advantage plans must include an annual out-of-pocket maximum, which provides financial protection that Original Medicare alone does not. You can enroll in a Medicare Advantage plan during the Annual Election Period (October 15 through December 7) or, in some cases, during other qualifying enrollment periods.
Exploring Medigap Plans K and L
If your health issues result in higher premiums rather than outright denial, Medigap Plans K and L may be worth evaluating. These plans have lower premiums than more comprehensive options because they cover a smaller share of cost-sharing. However, they include annual out-of-pocket limits — $7,000 for Plan K and $4,000 for Plan L in 2026 — which provide a safety net against catastrophic expenses.
Practical Steps to Protect Yourself
If you are thinking about leaving Medicare Advantage for Original Medicare, take these steps before making a final decision:
1. Determine Whether You Have Guaranteed Issue Rights
Review the qualifying situations listed above carefully. If you are within your first 12 months of Medicare Advantage enrollment, if your plan is leaving your area, or if another qualifying event applies, you may be able to purchase Medigap without underwriting. Confirm your rights before disenrolling.
2. Check Your State's Protections
Contact your SHIP counselor or your state's department of insurance to ask whether your state offers additional Medigap protections beyond federal law. If you live in Connecticut, Massachusetts, New York, or Maine, you generally have access to guaranteed issue enrollment regardless of your health.
You can find your local SHIP at Medicare.gov or by calling 1-800-MEDICARE (1-800-633-4227).
3. Apply for Medigap Before You Leave Your MA Plan
You can apply for a Medigap plan up to 60 days before your Medicare Advantage coverage ends. This allows you to know whether you will be approved before you finalize your switch. If you apply and are denied, you still have the option to remain in your current Medicare Advantage plan.
4. Apply to Multiple Insurers
Because each Medigap insurer sets its own underwriting criteria, a denial from one company does not necessarily mean denial from all. If your health conditions are borderline, applying to several insurers may increase your chances of approval. Premiums and underwriting standards vary across companies even for the same plan letter.
5. Understand the Timeline
If you have guaranteed issue rights, you generally must apply for a Medigap plan no later than 63 days after your prior coverage ends. Do not wait until the last minute. Gather your information, identify the Medigap plans available in your area, and submit applications promptly.
6. Keep Records
Document everything: your Medicare Advantage plan's termination notice, your disenrollment confirmation, and any correspondence with Medigap insurers. If a dispute arises about your guaranteed issue rights, having clear records will support your case.
Key Takeaways
Switching from Medicare Advantage to Original Medicare is straightforward from an enrollment perspective — but obtaining Medigap coverage to fill in Original Medicare's cost-sharing gaps can be far more difficult than many people expect.
Your ability to purchase a Medigap policy without medical underwriting depends on your specific situation: whether you have guaranteed issue rights, how long you have been in a Medicare Advantage plan, what state you live in, and your current health. In most states, if you have been enrolled in Medicare Advantage for more than 12 months and do not meet a qualifying event, insurers may evaluate your health and potentially decline coverage.
Before making the switch, assess your guaranteed issue rights, explore your state's protections, and apply for Medigap coverage before leaving your current plan when possible. For personalized help, reach out to your local SHIP office or call 1-800-MEDICARE. These resources are available at no cost and can help you understand the options that apply to your situation.